inconsistency in invoking method

[Brian Goetz]

This is correct.  What's happening is that in the first example, the 
most natural overload of map() is map(ToDoubleFunction) because the 
shape of the lambda provided most naturally matches Integer -> double, 
so it selects the overload that returns a DoubleStream, which has a 
sum() method.  In the second, it selects the map(Function), returning a 
Stream<Integer>, which has no sum() method.

If you do:

   Arrays.asList(1.0).stream().map(n -> (int) n).sum()
or
   Arrays.asList(1.0).stream().map(n -> Integer.intValue(n)).sum()
or
   Arrays.asList(1.0).stream().map(Integer::intValue).sum()

you'll get what you want.

(Keep repeating: we love erasure, we love erasure...)


On 3/3/2013 5:53 PM, Venkat Subramaniam wrote:
> Greetings,
>
> Not sure if this is by intent, but the following inconsistency is confusing and would be great
> if can be resolved:
>
>      System.out.println(
>        Arrays.asList(1.0).stream().map(n -> n * 1.0).sum()
>      ); //Works fine, prints 1.0
>
> However,
>
>      System.out.println(
>        Arrays.asList(1.0).stream().map(n -> n).sum()
>      ); //error: cannot find symbol
>
> Thanks
>
> Venkat
>